Radiologic Prevalence of the Round Window Niche Veil in a Japanese Cohort Using Ultra-High-Resolution Photon-Counting Detector CT

OBJECTIVE: To determine the in vivo radiological prevalence of the round window niche veil (RWNV) using the ultra-high-resolution (UHR) mode of photon-counting detector computed tomography (PCD-CT) and to assess variations in its prevalence across different age groups in a Japanese cohort. PATIENTS: This retrospective study analyzed temporal bone PCD-CT scans from 191 consecutive patients (382 temporal bones), aged 0 to 79 years. After excluding temporal bones with middle ear opacification or prior surgery, 261 temporal bones were included in the final analysis. INTERVENTION: All imaging was performed on a clinical dual-source PCD-CT scanner using a standardized, noncontrast UHR protocol. MAIN OUTCOME MEASURES: The presence of an RWNV was evaluated based on established radiologic criteria, requiring visualization of the characteristic soft-tissue shadow on both axial and coronal reformatted images. The primary outcome was the radiologic prevalence of the RWNV, calculated for the entire cohort and stratified by decadal age groups. RESULTS: An RWNV was identified in 66 of 261 temporal bones, yielding an overall prevalence of 25.3% (95% CI: 20.4%-30.9%). Prevalence varied across age groups, ranging from 5.3% (30-39 y) to 33.3% (40-49 y), but no consistent monotonic trend was observed with advancing age. CONCLUSIONS: This study provides the first large-scale, in vivo quantification of RWNV radiologic prevalence using UHR PCD-CT. The findings establish this advanced imaging modality as a valuable tool for noninvasively identifying this anatomic barrier, which has significant implications for predicting and potentially improving the efficacy of intratympanic drug delivery for inner ear disorders.